• 상하수도학회지
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• 제27권3호
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• pp.351-361
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• 2013

In this study the Principal Component Analysis (PCA) was applied to flow data in a water distribution pipe system to analyze the relevance between the flow observation dates, which have the outliers of observed night flows, and the maintenance records. The data was obtained from four small size water distribution blocks to which 13 maintenance records such as pipe leak and water meter leak belong. The flow data during four months were used for the analysis. The analysis was carried out to identify an appropriate analysis period for a PCA model for a water distribution block. To facilitate the analyses a computational algorithm was developed. MATLAB was utilized to realize the algorithm as a computer program. As a result, an appropriate PCA period for each of the case study small size water distribution blocks was identified.

• The Korean Journal of Physiology and Pharmacology
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• 제16권6호
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• pp.387-392
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• 2012

In this study, we examined the antinociceptive effect of Cyperi rhizoma (CR) and Corydalis tuber (CT) extracts using a chronic constriction injury-induced neuropathic pain rat model. After the ligation of sciatic nerve, neuropathic pain behavior such as mechanical allodynia and thermal hyperalgesia were rapidly induced and maintained for 1 month. Repeated treatment of CR or CT (per oral, 10 or 30 mg/kg, twice a day) was performed either in induction (day 0~5) or maintenance (day 14~19) period of neuropathic pain state. Treatment of CR or CT at doses of 30 mg/kg in the induction and maintenance periods significantly decreased the nerve injury-induced mechanical allodynia. In addition, CR and CT at doses of 10 or 30 mg/kg alleviated thermal heat hyperalgesia when they were treated in the maintenance period. Finally, CR or CT (30 mg/kg) treated during the induction period remarkably reduced the nerve injury-induced phosphorylation of NMDA receptor NR1 subunit (pNR1) in the spinal dorsal horn. Results of this study suggest that extracts from CR and CT may be useful to alleviate neuropathic pain.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제28권4호
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• pp.274-279
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• 2002

The purpose of this study is to evaluate the critical maintenance period of absorbable membrane for guided bone regeneration. Fortynine Sprague-Dawley rats weighing about 300g were divided into seven groups. An 8 mm circular full-thickness defect in calvarial bone was made and then cellular acetate porous filter (Millipore $filter^{(R)}$.) was placed on the calvarial bone defect. The filter was removed at 2, 3, 4, 5, 6, 8 and 11 weeks after placement. Rats were sacrificed at 12 weeks the placement of cellular acetate porous filter. The specimens were stained with Hematoxylin-Eosin and observed under light microscope. The amount of regenerated bone was measured from both margin of calvarial bone defect (unit : mm). The results were as follows. Bone regeneration of each experimental group was increased gradually and the bond defect was almost completely filled with new bone in 5-, 6-, 8-, and 11-week experimental group. Histologic findings showed mild inflammatory response and granulation tissue formation without apparent adverse effects on the healing process. In 11-week experimental group, the bone defect was completely filled with new bone containing abundant osteoid which was oriented to the dural side and contribute to bony thickening. We suggest that non-absorbable membrane and bioabsorbable membrane presumably should remain intact for longer than 5 weeks to be effective.

• Asian-Australasian Journal of Animal Sciences
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• 제27권1호
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• pp.30-35
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• 2014

This study was conducted to evaluate the protein requirement for maintenance of 2-year-old female Korean spotted deer. In the course of the experiment, each of three hand-reared female spotted deer was fed three diets that were iso-calorically formulated to contain low (approximately 7%), medium (12%), and high (17%) levels of crude protein (CP). Each of six trials included a 5-day transition, a 10-day preliminary, and a 7-day collection period. Dietary protein levels affected the apparent digestibility of CP (p<0.05) but not the apparent digestibility of dry matter, organic matter, or acid detergent fiber. All of the deer showed a positive CP balance on all of the diets. The maintenance CP requirement estimated by regression analysis was 4.17 g/kg metabolic body weight $(W^{0.75}){\cdot}d$. The maintenance digestible CP requirement was 1.42 g/kg $W^{0.75}{\cdot}d$. The metabolic fecal CP was 1.95 g/kg $W^{0.75}{\cdot}d$. The blood urea nitrogen of spotted deer increased (p<0.05) as the dietary protein levels increased.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 춘계학술대회 및 창립 30주년 심포지엄(논문집)
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• pp.339-344
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• 2006

컨테이너 터미널의 생산성의 주요 지표로서 선박작업 생산성이 강조되고 있으며, 이는 갠트리 크레인의 작업에 크게 의존되고 있다. 갠트리 크레인의 작업시간에 발생되는 고장시간 및 고장수리시간에 의해 크레인의 본선작업 가동율이 결정되며, 이로서 체선시간이 좌우되고 있다. 본 연구에서는 갠트리 크레인의 예방보전 주기를 새롭게 설정함에 의하여 크레인의 고장을 감소시키며, 이로서 선박작업 생산성에 미치는 영향을 지표로서 제시하고자 한다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권3호
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• pp.246-255
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• 2017

Purpose: This study proposes the optimal PM (preventive maintenance) policy of leased equipment for lessee's decision-making using two types of reliability condition. Methods: We consider reliability threshold based PM model. Equipment reliability is estimated and used as condition variable. The effect of repair for maintenance is imperfect and represented by age reduction factor. Results: We provide two PM policies. Policy 1 is focused on minimized total cost. This policy guarantees reliability threshold until last maintenance action. Policy 2 focus on maintaining reliability threshold during leased period. The proposed approach provides optimal reliability threshold under number of PM. Through result, we finally construct decision-making process for lessee using reliability threshold and end of reliability. Conclusion: This study provides two PM policy for lessee's decision-making. Through numerical example, we get a result of optimal reliability threshold, number of PM, optimum alternative under lessee's reliability condition.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.79-87
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• 2008

The major objective of this study is to investigate the effective maintenance system for the infrastructure on the conventional lines in which the tilting train runs. In order to the speed-up of conventional lines that have many curve lines, there needs a improvement construction of substructure such as the straight or double track work and so on. But in this case, it needs to have a plenty of the cost and the period. Therefore, the tilting train which provides the high-speed service effectively in curve tracks was developed. Besides, the efficiency prediction and the linear fitness of the existing conventional lines for a tiling train service were examined on the preceding study which was the development of track system innovation technology for speed-up of them. So, in this paper we propose the more effective maintenance method than the existing it in order to securing the high reliability and safety classified by the infrastructure, in analyzing foreign materials and the maintenance as well as the inspection cycle concerning domestic infrastructures of the track and the catenary etc. on the railway. And we look forward to playing a decisive role as reference material for the effective improvement of the existing maintenance about the infra on the conventional lines for the commercial service of the tilting train.

• 플랜트 저널
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• 제12권2호
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• pp.31-35
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• 2016

본 연구에서는 발전 플랜트의 보일러 급수 펌프를 대상으로 신뢰도 기반 정비를 적용하기 위한 고장 데이터 관리에 관한 방법에 대하여 논의하였다. OREDA와 같은 고장 데이터베이스에서 중요한 구성 요소인 고장모드, 고장원인, 고장영향, 고장의 심각도를 분석하는 것이 신뢰도 기반 정비에서 중요한 부분이다. 정비주기와 같이 예방 정비 계획을 세울 때 중요한 부분은 고장 데이터의 통계적 처리로부터 결정될 수 있음을 확인하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.81-82
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• 2015

BIM has been a reliable construction project management tool to handle various kinds of construction information generated in the facility life cycle. To take these advantages, researchers have been promoted numerous studies in a residential, a commercial, and an educational facilities with a large number of on-going projects. However, despite running as the role of essential energy supplier, power plant related BIM research is relatively insufficient than others. In particular, due to the extending of the facility service period and the requirement of the complicated construction project management for 'overhaul' and 'repowering' in the power plant maintenance phase, the needs for using BIM have been increased gradually. For using BIM based maintenance, it is needed to consider an information collecting methods and necessary to develop an appropriate breakdown structure to share information. Therefore, 'EBS' is produced by reviewing the previous research related to BIM and analyzing the repair activities in the maintenance phase. Proposed 'EBS' must be useful not only a judgment between capital expenditure versus revenue expenditure but also appropriate maintenance strategies development for property management.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1308-1314
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• 2008

In this paper, Seoulmetro that is the first operation organization which operates a city railroad rolling-stock maintenance RIMS(rolling stock information maintenance system) collected and analyzed a light maintenance data and introduced time a series analysis technique to find the way how to contribute to a use efficiency improvement of a city railroad. The purpose of time a series analysis is to remove a seasonal change including data and to check an irregular fluctuation. First of all, a collection range of the data comes under a light maintenance, however it needs a data of more than 3 years to check the seasonal change. We put a study for an accumulated scope that the data satisfy a period like this and are able to extend a range of the study when time flys forward. The data used for study is filtered using a movement average method after passing proper selection working and is solved with a method which looks for season index. Using the season index that was getten in here, we predict a light working frequency, if it has an irregular change, we will contribute it to a city railroad a use efficiency improvement and establish the cause by carrying out prevent maintenance in advance.